Switch-board for electric circuits



(No Model.)

E. BLAKE.

SWITCH BOARD POR ELECTRIC CIRCUITS.

Patented Apr. 24, 1883.

Fig 2 Tl/Tlifnesses: t @ff/67,4 @www rvr UNITED STATES PATENT OFFICE.

FRANCIS BLAKE, CF INTESTCN, MASSACHUSETTS.

SWITCH-BOARD FOR ELECTRIC ClRCUlTS.

SPECIFICATION forming part of Letters Patent No. 276,216, dated April24, 1883. Application tiled February 3, 1SS3. (No model.)

To all whom it may concern:

Be it known that I, Farmers BLAKE, of Weston, in the State ofMassachusetts, have invented a new and useful Improvement inSwitch-Boards for Electric Circuits, ot' which the following is aspecification.

The invention is an improvement upon the switch-board described andclaimed in my Patent No. 249,574, dated November 15, 1881.

In carrying out the said former invention I formed the switch-boardproper oi alternate plates of conducting and non-conducting material,each of the full size ofthe board, and a number of smaller metallicplates, one for each of the electric circuits between which connectionswere to be made. The smaller metallic plates were secured to one of thelarge insulating-plates and served as line terminals. The large platesof conducting material served as connecting-plates, since any one ofthem could be made to make electrical connection between any two lineterminals, the method of makin g such electrical connection being asfollows: A hole bored through each terminal plate and all the largeplates, both the nonconducting plates and the insulating-plates,

allowed a connection to be made between any terminal plate and anyconnecting-plate by means of a metallic peg of the proper length havingtwo iianges, one of which, when the peg was inserted in one ot' saidholes, made contact with the terminal plate, while the other madecontact with a connectingplate. A pair of pegs was appropriated to eachconnectingplate, and any pair of pegs would make connection between anytwo terminal plates by means ofthe connecting-plate, to which they wereappropriated. The principal advantage of this former switch-boardconsists in the compactness and rigidity or absolutely fixed position ofthe connecting-plates, but its use is attended by the disadvantage ofhaving a very limited capacity, owing to the diliiculty in using pegs ofmore than a certain length. When pegs are used, as described in my saidPatent No. 249,574, only about as many connections can be made by asingle set ot" the connecting and insulating plates as can besuperintended by, at most, two or three operators, whereas in largetelephone cachan ges it is frequently necessary to employ a large numberot operators, each having in charge as many line terminals as can beplaced upon the switch-board ot' my said former patent, and provisionmust be made for the use of a common set ot' connectors by all theoperators.

The object of this improvement is to retain in a switch-board ofpractically unlimited capacity an advantage similar to that resultingfrom the use of the said large and iirmly-seated connecting-plates in mysaid former switchboard; and the present invention consists ot'alternate strips or long plates of conducting and non-conductingmaterial and a number' of line terminals, one for each of the electriccircuits between which connections are to be made, in combination with anumber ot' metallic rods, one for and in constant contact with each ofsaid line terminals, and provided with a spring device, whereby each rodmay be put in electrical connection with either of said strips or longplates of conducting material.

It consists, further, in certain details oi' construction.

ln the drawings, Figure lis aplan, and Fig. 2 a section, of so much ofan apparatus for carrying my improvement into effect as willsufticiently illustrate the same.

P is a bed of insulating material, to which are secured in any propermanner the conducting strips or plates c and insulating strips or platesi, massed together face against face, as shown.

g is a metallic plate, screwed to the edge ot the bed-plate I), asshown, and forming, with one of the connecting-strips with which it isin contact, a ground-plate, the ground-wire being shown at g.

t t are metallic brackets, screwed to the hed, as shown, and forconvenience made the line terminals, the line-wires being shown at Z Z2l, &e. Cue arm of each bracket t contains a bearing for a line-rod, r,so that each linerod is in constant contact with a line terminal, andone line terminal only. Another bearing ior each line-rod is in one ofthe insulated metallic plates b, of which there is one foreach line, andwhich might be made the line terminals in place of the brackets t. Holesh h are bored through the mass ot' conducting and iiisiilating plates cc i as t'ar as the plate g, somewhat larger iii diameter than thedianieterot' the rods o', and in these holes the rods i' are insertedand have a sliding'motioii while supportediu the above-mentionedbearings. Each rod r has upon its farther end two contactsprings, S,(one would be sutlicient,) which make Contact with some one oftheconnectingplates c, according to the position of the rod. A scale,graduated to the distances between the centei's of theconnecting-plates, is placed upon the bed-plate in iront of the niass ofconnecting and insulating plates, and each rod carries a pointer,p,which indicates the position of the contact-spring. rEhus at Fig. l thepointers of the rods lr appropriated to lines Z2 and Z6 indicate thatthe contact-springs c of those rods are in contact with the saineconnecting-plate, and consequently that the said lines are in metallicconnection. rllhe lines Z3 and lAL are also iii metallic connection,wliile lines l and l5 are grounded. lt is obvious that the rods r maythemselves serve as line terininals.

For the purposes ot' this specification the board shown at Fig. l may beconsidered as a single board under the charge of a single operator, oras three separate boards of two lines each requiring three operators, asindicated by the dotted lines .r a', and it is obvious that the rods rot' the lines Z and Z6 may be at any required distance apart; and, whilethe coiinecting-plates c may thus be of any required length, it willalso be obvious that the number ot' connecting-plates may be practicallyunlimited, when it is stated that the con nesting-plates need not bemore than two thirty-seconds of an inch, and the insulating plates onethirty-second oi an inch in thiclness. Since the contact with theconductingplatesisniadebyaspring,theinsulating-plates may be veryconsiderably thinner than they must be in practice when the contact isto be made by the iiange of a peg. lt will be observed that in thedrawings the insulatingplates i are represented by heavy black lines. Ipret'er the construction shown, in which provision is made that thelille-rods r with their spring-contact points travel back and forth iiiholes bored through the mass ot' conducting and insulating plates, sincethe holes are free from dust and a good contact is insured therein, andl claiin this speciiic form of construction as a subordinate part of myinvention; but without departing from my inveiition, broadly considered,the line-rods carry ing a spring-contact .device may be arranged totravel on the outside of the mass ot' connecting and insulating plates;or a suitable spring-contactdevice may be made to travel over the massof connecting and insulating plates on lille-rods rigidly secured to theline terminals. The switch-board as a whole, including the switchingapparatus, when made according to one or the other otl theseinediticatioiis, closely resembles the board in one or the other of itsforms described and claimed in my Patent No. 243,839, but differstherefrom in the nature. of the stationary conductors employed and inthe method of insulating` said stationary conductors. In theconstruction shown in Patent No. 243,839, it is exceedingly difficult tokeep the tine wires in their proper slots and maintain their insulation,while in the present construction and modifications thereof abovenientioned not only may the conducting strips or plates be fixed singlyin any immovable position desired, but, when they are put together in amass, as described, each helps to support every other. Indeed, it isobvious that by the use of properly-insulated bolts and other insulatorsthe inass ot' conducting and noncoiiducting plates may be made itselt'to serve as a frame for the support ot' the remainder ot' the switchingapparatus.

I claiml. Alternate strips or long plates of conducting audnon-conducting material put together in a mass and a number ot' lineterininals, in combination with a number of conducting-rods, one for andin constant contact with each of said line terminals, and each ot' saidrods provided with a springcontact, wlierebyit may be put in electricalconnection with either ofthe said strips or plates ot'conductingmaterial,substantially as described.

2. The combination, with alternate plates of conducting andnon-conducting material put IOO together in a mass and provided withholes extending through the mass, ot' a number of metallic rods, eachsecured in one ot' said holes, but having a longitudinal movement,substantially as described.

o. The combination, with the conductingplates c and insulating-platest', provided with the holes h, ofthe line terminals t and rods i, thelatter provided with spring-contact c, substantially as described.

4. The combination, with the conducting plates c and insulating-platest', provided with the holes 7i, of the line terminals t and rods i', thelatter provided with spring-contacts c and pointers j), substantially asdescribed.

FRANCIS BLAKE. Witnesses:

W. W. SWAN, WM. S. Roenes. y

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